The CPU has a 77 watt tdp, the z75 chip set probably consumes another 5 watts, the ram maybe another 2-3, the ssd is almost nothing, less than 1 watt from what I've read and the video card has an 85 watt tdp.

The grand total is about 170 watts, idle hopefully in the 20s.

So what PSU? It might be possible to run it on a picopsu with a big power brick and an independent PCIe 12v cable but that's expensive, not guaranteed efficient and involves quite a bit of diy.

A conventional ATX PSU would work but its hard to find low wattage, high efficiency and cheap in the same PSU.

What I'm going to do is a good DIY project. I found a used, not quite ATX standard, 80+ silver rated 250 watt PSU from a somewhat common line of fairly decent computers. The best part: it was cheap.

The project is that the OEM was going cheap so the ATX cable is very short. They were not worried about upgrades so no PCIe 12v cable and the combination of SATA, FDD and molex connectors does not match my system.

A large order from modDIY will fix that.

Its probably not price competitive with the other options but I'll have plenty of spare connectors, cable sleeving, crimp tools and wire strippers to do a few more projects so I'm in.

Status right now: I have my PSU, I'm scavenging the ATX cable from an obsolete PSU to extend it (instead of buying 5-6 spools of wire in the right colors) and I'm waiting for my modDIY order to arrive.

The not so good: the PSU uses an 80mm fan and two circuit boards so retrofitting a 120 is not possible but the computer had a noise spec of 26 dB I think and since it only has to dissipate ~36 watts max, hopefully it is fairly quiet. The size isn't ideal either, its taller than ATX. I think it will fit in my case but the motherboard might interfere (I haven't checked yet, fingers crossed). Its also that lovely galvenized steel color so a bit of spray paint might happen.

Last edited by QUIET! on Sat Jun 15, 2013 3:27 am, edited 1 time in total.

So what PSU? It might be possible to run it on a picopsu with a big power brick and an independent PCIe 12v cable but that's expensive, not guaranteed efficient and involves quite a bit of diy.

There are a few people here who managed to get a Dell DA-2 to cooperate with a picoPSU, whilst diverting 12V also directly to a graphics card. I'm not sure how costly your OEM product was; the Dell bricks then to sell very cheaply on eBay.

I got the CPU cooler bracket I was waiting for, quickly populated the motherboard, screwed it in to the case and when I test fit the power supply: it doesn't fit.

Its taller than ATX standard so it covers up the row of USB and assorted headers at the bottom of the motherboard.

I've got one hail Mary to throw at it but I'm not terribly optimistic.

It looks like it may be possible to fit the guts in a modified ATX PSU case. Although there are two circuit boards, there is space between them so squeezing them together may allow them to fit a smaller case. Secondly, it looks like one of the circuit boards mounts the same as the single board in my Enermax so I may only have to find a way to mount one of the boards.

I checked my tracking and found that my new PSU is on the big brown truck, out for delivery today.

I also did a little Google search and found that the PSU only misses 80+ platinum spec by 1% at 20% and 50% load.

Looking at the length of the cables, I may only have to modify five wires, all crimps, no solder and no need to open the case. It should be a very simple DIY with most of the work getting the routing right and sleeving the cables for looks.

I want to sheath my cables so that's one of the first things I started today but before that I bought one of those handy coolmax PSU testers with LCD screen.

The tester is cool, you begin a test by plugging in the 20 or 24 pin ATX cable and the ATX12v 4 or 8 pin cable, then you press a button which fires up the PSU, displays the 12v, -12v, 5v, 5vsb, 3.3v voltages and the power good timing.

After that you can plug in your PCIe 12v 6 or 8 pin cable, a SATA power cable, a molex cable or a floppy drive cable and it will tell you if the connections are good.

Any way, I sheathed my ATX cable then tested. I got a fail. It said the power good signal was taking too long. I tried another PSU and it passed. I was starting to get discouraged but then I measured the power good (gray) wire and found about 4.5v.

Power good is supposed to be 5v and I don't know how much voltage the PSU tester needs to see but I decided to take a chance and see if the computer would post. The first step to that was to remove my video card because currently the PSU has no PCIe 12v connector, then I rigged up an ATX12v extension because the existing one is too short. I didn't want to chance frying any more hardware than necessary so I removed one stick of ram and did not hook up any SATA devices.

The result of my test was a successful POST and entry in to bios. The computer beeped once and then just ran. The noise was quite low in volume, low enough that I initially thought that I failed to POST because I did not have my HDTV set to the right input.

A further result is that I have to open up the PSU to add cabling, there isn't enough to just add the right connectors on to existing cables. Luckily I can test all of my connections before I put it back in the case so my confidence level is high.

I would have gotten more done today but I ran in to two problems, not enough wire in the right color and my new crimp tool sucks. I'll see what I can do about that tomorrow.

I am fairly pleased with the results, everything fits now with no extra wires flopping around.

The only thing I didn't do is sheath my SATA power cable because my crimper sucks and I didn't want to cut cables and make more butt joints. If I ever get a decent crimper I will change that.

The PSU still failed the power good test but continues to work fine when in the computer.

I had my SATA data cables, I was able to hook up both my BD drive and SSD so I got to install my operating system.

I chose Windows Home Server 2011 because its the cheapest legitimate 64 bit Windows OS you can buy, its based on a stripped down Windows 2008 Server OS and the parts that they stripped down I probably don't want any way.

Installation hit a small snag when it couldn't find drivers for my onboard Intel 82579V NIC. From what I've read on the internet, that is a common problem with Windows Server 2008 and integrated Intel NICs and the solution may be simple.

One thing I was able to do is stop the windows installation with the task manager and I've already got a more or less complete OS. I was able to install my graphics drivers from CD and fool around a little although there isn't much to do without a network connection.

I would have liked to do benchmarking and power consumption tests but that will have to wait (Tuesday maybe).

My os is almost installed, I got my on board gigabit Ethernet installed by modifying an .inf file the same way as Server 2008r2 and it even has the correct V device name, not the LM that forcing the driver will do.

My Cyber Power 850pfclcd ups is supposed to display power but it seems to fluctuate between 40 watts and 0 watts. The 0 watts is obviously incorrect so I bought a Kill-A-Watt to get a real reading.

I haven't been able to load test but idle is pretty spectacular, roughly 23 watts!

Its not an i5 yet, I still have my i3-3220 installed. Once I have my software installed, benchmarked and stress tested I will upgrade but I don't expect a huge increase in idle power.

This test includes an Asus Radeon 7790 GPU installed with the driver on the installation CD.

There is no HDD, just a Samsung 840 Pro 256 GB SSD.

The ram is Samsung green DDR3, 2x4gb.

The motherboard is an Intel dz75ml-45k micro-ATX. That's a budget board but still a Z chip set which allows over clocking K processors and only lacks the HDD caching SSD functionality and maybe one or two other things I won't miss.

There is also an LG SATA BD/DVDrw optical drive, a wireless keyboard/mouse dongle and a Patriot B/G/N WiFi mini-dongle installed.

Two Cougar low rpm pwm fans and a Xigmatek 1284 something CPU cooler.

The PSU is a Dell 255 watt 80+ gold certified, used PSU which I had to add a PCIe 12v cable for the Radeon 7790.

Stress testing is critical, if the PSU can't take it, I'll have to upgrade but this thing idles so low I can't explain it.

My fans did throttle up during the GPU and PSU load tests but the noise level is not too bad.

The verdict: my i3 seems to draw about 40 watts more power at load than idle. If it draws 7 watts (to keep the math easy) at idle, that means a 77 watt TDP i5 could draw about 30 watts more power which means ~195 watts at PSU test type loads and assuming 90% PSU efficiency, that's about 162 watts, quite close to the number made by adding the TDPs and less than 65% of my 255 watt PSU rating. The PSU hasn't popped so far, I think it can handle an i5.

The PSU is a Dell 255 watt 80+ gold certified, used PSU which I had to add a PCIe 12v cable for the Radeon 7790.

Interesting read thanks. Do you happen to have the specific model number for the dell PSU you used?

I'm building a replacement low-power home server for my aging underpowered HP microserver N36L, and I'm struggling to find any low-power efficient PSU's, so getting one of these Dell ones might be the ticket (I'm prepared to mod - I have everything from a soldering station to a mig welder ).

The numbers you're getting look to be better than a pico+brick combo, which matters more to me for this build than silence as my home server cabinet is in the garage.

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